The exceptional preservation of the Lower Cambrian Chengjiang Lagerstätte
provides a unique insight into the early evolution of vermiform animals. This study
presents new vermiform taxa, describes their morphological features, hypothesizes
possible modes of life and discusses phylogenetic relationships among early metazoan
phyla.
Morphological features are re-assessed in the Cambrian lobopodian Luolishania
longicruris, and Miraluolishania haikouensis is considered to be its junior synonym.
Evidence indicates that L. longicruris may have had a filter feeding lifestyle. Cladistic
analysis suggests that Cambrian lobopodians are paraphyletic or even polyphyletic, and
that L. longicruris with well developed sensory structures (‘antennae’, eyes and setae)
and tagmosis (a distinct head and two trunk sections) may be an important
representative of the stem lineage leading to arthropods.
A new fossil priapulid Eximipriapulus globocaudatus is reported and described on
the basis of specimens that reveal exquisite morphological details. Possible internal
fertilization is suggested and a putative juvenile is described. Evidence indicates that the
animal was an active burrower using a double-anchor strategy. Cladistic analysis
resolves E. globocaudatus as one of the most derived Cambrian stem priapulids.
The eyes of Hallucigenia fortis and Cardiodictyon catenulum are reported, along
with a re-description of eyes from L. longicruris. Three visual units are found within the
eyes of H. fortis and L. longicruris, suggesting that they resemble arthropod lateral
visual organs and appear to represent the primitive visual systems of arthropods.
Three new vermiform taxa, Acanthipos torquatus, Hamuscolex bosolveri, and
Palaeomyzon discus are described. Comparison with extant taxa suggests that they may
be stem group representatives of three separate phyla of extant parasitic worms. The
oral disc of Palaeomyzon discus indicates a parasitic lifestyle. This study extends both
the biodiversity and ecological diversity of known Early Cambrian ecosystems.